Three women allegedly held as slaves for 30 years  in a house in south London may have been part of a semi-religious cult, it has been reported.

Police rescued a 69-year-old Malaysian woman, a 57-year-old Irish woman and a 30-year-old British woman, after they contacted a charity claiming they had been living a life of servitude for decades.

A 67-year-old couple have been arrested on suspicion of slavery charges and bailed.

Yesterday, police described the case as a "complicated and disturbing picture of emotional control over many years".

The woman were allowed "limited freedom" such as going outside to hang washing, or occasional shopping trips accompanied by one their captors.

And according to The Guardian, sources close to the investigation believe this relationship amounted to something similar to a 'semi-religious cult'.

Police have said it will likely take them months to fully understand exactly what happened in the Lambeth house.

Met Police Commander Steve Rodhouse told a press briefing his team are "unpicking a story that spans at least 30 years of these women's lives".

He said that to the outside world they may have appeared to have been a "normal family".

"This does mean that over the course of many decades the people at the heart of this investigation, and the victims, would probably have come into contact with public services, including our own," he said.

"That's something we need to examine fully.

"What I can say with some certainty is that the two suspects in this case were arrested by the Metropolitan Police in the 1970s, some considerable time ago."

No more details on those arrests were given.

He said the investigation will take "some considerable time", and there are a number of lines of inquiry to follow up, numerous statements to take and lots of exhibits to examine.

Mr Rodhouse said police do not believe the case falls into the category of sexual exploitation or what is traditionally referred to as human trafficking.

"It is not as brutally obvious as women being physically restrained inside an address and not being allowed to leave," he said.

He said police are trying to understand "what were the invisible handcuffs being used to exert such a degree of control over these women".

He said that to label the investigation as domestic servitude or forced labour is "far too simplistic".